In the last 50 years, scores of dogs have jumped to their deaths from the bridge approaching Scotland’s Overtoun House. All the dogs have jumped between the final two parapets on the right-hand side, and nearly all have jumped on clear, sunny days. The dogs tend to be long-nosed breeds, labradors, collies, and retrievers.

It’s unlikely that the dogs are seeing something, because from their perspective little is visible. Acoustic experts have detected no unusual sounds. But mice and mink live under the bridge, and animal habitat expert David Sands found that the dogs he tested were strongly drawn to mink scents. Mink were introduced to Scotland in the 1920s and would have produced a significant population by the 1950s, when the jumps started occurring. The scents left by their anal glands would be strongest in dry conditions and most accessible to keen-nosed dogs with long snouts.

“When you get down to a dog’s level, the solid granite of the bridge’s 18-inch thick walls obscures their vision and blocks out all sound,” Sands told the Daily Mail. “As a result, the one sense not obscured, that of smell, goes into overdrive.”